Sewing machine



Sept. 6, 1938. L. s. BOWMAN ,1

SEWING MACHINE Filed Sept. 27, 1955 15 Sheets-Sheet l Q PB:

INVENTOR. 1702a; G. aowmazu.

ATTORNEY Sept. 6, 1938. 1.. G. BOWMAN- 2,129,402

7 SEWING MACHINE Filed Sept/2'7, 1955 15 Sheets-Sheet 2 IN VEN TOR.

A TTORNEY Sept. 6, 1938. G. BOWMAN SEWING MACHINE Filed Sept 27, 1955 15Sheets-Sheet 5 INVENTOR.

Z0242 G-Jowmam ATTORNEY L. G. BOWMAN SEWING MACHINE Sept. 6, 1938.

Filed Sept. ,27, 1955 15 Sheets-Sheet 4 INVEN'TOR. lZzzzJ 6- Jawmam IATTORNEY Sept. 6, 1938.

| G. BOWMAN SEWING MACHINE l5 Sheets-Sheet 5 w? INVENTOR. F louwzziawmmz.

. ATTORNEY Filed Sept. .27, 1935 Sept. 6, 1938. L. G. BOWMAN.

SEWING MACHINE Filed Sept. 27, 1935 15 Sheets-Sheet e INVENTOR. lauds G.@owman. BY'

A TTORNEY Sept. 6, 1938. L. G. BOWMAN SEWING MACHINE Filed'Sept. 2'7,1935 15 Sheets-Shee '7 gWQ A I INVENTOR. I Iouw aowmm.

TTORNEY A 22/ lm L. G. BOWMAN SEWING MACHINE Sept. 6, 1938.

Filed Sept. 27, 1935 15 SheetS-Sheet 8 kkwu E INVENTOR. IOZZ J G. owmam.

ZZTTORNEY SEWING MA NE Filed Sept. 27, 1935 15 Sheets-Sheet 9 I NTOR.Iaui G. :Zawm

BY I

ATTORNEY Sept. 6, 1938. G. BOWMAN SEWING MACHINE Filed Sept. 27, 1955 15Sheets-Sheet 10 INVENTOR. Iouzli G. owmm BY 18? "7Z3:

A TTORNEY L. G. BOWMAN SEWING MACHINE Sept. 6, 1938.

Filed Sept. 27, 1935 15 Sheets-Sheet 11 INVENTOR. 02428 6. 5owmam l BY 5j ATTORNEY- Sept. 6, 1938. 1.. G. BOWMAN 2,129,402

SEWING MACHINE Filed Sept. 27, 1935 15 Sheets-Sheet 12 i I I i i l l lINVENTOR Zouw 6. czowman.

ATTORNEY Sept. 6, 1938.

| G. BOWMAN SEWING MACHINE Filed Sept. 2'7, 1935 15 Sheets-Sheet l3 1NVEN TOR. 17020.5 61. czawmam.

BY Ta l-fm A TTORNEY Sept. 6, 1938. L. G. BOWMAN I SEWING MACHINE File dSept. 27, 19:55

15 Sheets-Sheet 14 i INVENTOR.

- l'ouzs 6. Zowmazu.

BY ATTORNEY 15 Sheets-Sheet 15 Sept. 1938. G. BOWMAN} SEWING MACHINEFiled Sept. 27; 1935 IN V EN TOR. $0 wmam' "7325- A TTORNE Y I 5 w. IN TM. m 1 R Ida BY 5* Patented Sept. 6, 1938 UNITED STATES PATENT OFFICESEWING MACHINE Application September 27, 1935, Serial No. 42,547

31 Claims.

This invention relates to new and useful improvements in sewing machinesgenerally, although more particularly to those of the blind stitch type.

Sewing machines have heretofore been devised which are capable offorming anchor and skip stitches in alternation. In the Mueller Patent2,018,186, Oct. 22, 1935, there is disclosed a machine in which isembodied means for forming blind stitches, means for normally projectingthe hem fold and body fabric and then the hem fold only into positionfor needle penetration whereby alternate anchor and skip stitches willbe formed. There is provided also manually controllable means forcausing the formation of successive anchor stitches without forming anyskip stitches.

An object of my invention is to provide novel and improved mechanismsfor forming anchor and skip stitches, there being included adjustabledevices by employment of which the operator is enabled to effect theformation of a succession of anchor stitches; or alternated anchor andskip stitches, there being one skip stitch intervening each pair ofanchor stitches; or alternated anchor and multiple skip stitches, therebeing a multiple of skip stitches intervening each pair of anchorstitches.

With this and other objects in view which will more fully appear, thenature of the invention will be more clearly understood by following thedescription, the appended claims, and the several views illustrated inthe accompanying drawings.

In the drawings:-

Figure l is a front elevation of the machine.

Figure 2 is a right end elevation.

Figure 3 is a left end elevation.

Figure 4 is a rear elevation.

Figure 5 is a top plan View.

Figure 6 is a horizontal section through the standard at the point ofpivot of the work support or table, portions of the latter being shownbroken away and in section.

Figure '7 is a face View of the larger gear of the l-to-Z ratio set ofgears.

Figure 8 is a face view of the larger gear of the l-to-4 ratio set ofgears.

Figure 9 is a detail vertical longitudinal section through the axis ofthe gear ratio selecting mechanism. Figure 10 is a detail perspectiveView of the pivoted lever by which the gear ratio selection is made.

Figure 11 is a detail vertical sectional view illustrating the dualspring mounting of the work support or table.

Figure 12 is a somewhat diagrammatic vertical cross sectional Viewillustrating the ridge forming element shifting devices shifted toposition 5 for causing the formation of an anchor stitch during eachneedle operation or main shaft rotation, the 1-to-2 gear ratio beingshown as effective.

Figure 13 illustrates the position of the ridge forming element andoperating cam effected by the position of theparts as shown in Figure12.

Figure 14 is a detail vertical longitudinal section taken along the axisof the pivot pin shifting means shown in Figure 12. 15

Figure 15 is a somewhat diagrammatic vertical cross sectional viewillustrating the ridge forming element shifting devices shifted toposition for causing the formation of a single anchor stitch during eachfourth needle operation or main shaft rotation, skip stitches alonebeing formed during intervening needle operations or main shaftrotations, the l-to-4 gear ratio being shown as effective.

Figure 16 illustrates the position of the ridge formingelement andoperating cam effected by the position of the parts as shown in Figure15.

Figure 17 is a detail horizontal section taken along the axis of thespring pin which yieldably retains the adjustment of the pivot pinshifting lever.

Figure 18 is a somewhat diagrammatic vertical cross sectional viewillustrating the ridge forming element shifting devices shifted toposition for causing the formation of a single anchor stitch duringevery other needle operation or main shaft rotation and skip stitchesduring the intervening alternate needle operations or main shaftrotations, the 1-to-2 gear ratio being shown as effective.

Figure 19 illustrates the position of the ridge forming element andoperating cam effected by the position of the parts shown in Figure 18.

Figure 20 is a detail vertical longitudinal section through the ridgeforming element support cam plate and its mounting.

Figure 21 is an enlarged detail plan view illustrating the work clampand the supportingtable extension end.

Figure 22 is an inverted plan view of the parts shown in Figure 21, theprotective casing member being shown removed. v

Figure 23 is a detail sectional view illustrating the transverse pivotmounting and spring support of the work clamp.

Figure 24 is a somewhat diagrammatic sectional view illustrating thefeature of automatically releasing thread tension by depression of thework support or table.

Figure 25 is a detail view illustrating the driving connections for theneedle.

Figure 26 is a detail inverted plan view of the sewing head and theparts supported thereon.

Figure 27 is a detail plan View of the rigid presser foot and threadlooper removed from their support.

Figure 28 is a detail cross section taken on the line 28-28 on Figure27.

Figure 29 is a detail cross section taken on the line 29-29 on Figure27.

Figure 30 is a detail longitudinal section taken on the line 3030 onFigure 27.

Figure 31 is a detail view illustrating the driving connections for thethread looper.

Figure 32 is a detail perspective view of the needle shaft take-upbearing.

Figure 33 is a detail perspective View of the extension bearing for themain shaft.

Figure 34 is a diagrammatic plan view illustrating the formation of aseries of anchor stitches, the thread arm or looper being shown in theprocess of laying the needle thread over the edge of the hem fold.

Figure 35 illustrates the completion of the thread laying movement shownin Figure 34, the needle being shown in the process of carrying theneedle thread through the loop laid by the thread looper fingers. I

Figure 36 illustrates the continuation of the stitch formation shown inFigures 34 and 35, the needle having receded and left a slack needlethread which has been taken up by the hook and is being passed aroundthe bobbin thread, and the thread looper being shown as starting towardformation of its function shown in Figures 34 and 35.

Figure 37 is a detail view of the thread looper end and illustrates themanner in which the yieldable thread looper finger clears the needle inreceding from the thread laying function shown in Figure 35.

Figure 38 is a detail end elevation of the thread looper.

Figure 39 is an enlarged somewhat diagrammatic plan View of a portion ofa seam showing a plurality of anchor stitches at each end and alternateskip and anchor stitches intermediate said ends.

Figure 40 is a View similar to Figure 39 and illustrates the seamembodying anchor stitches at the beginning or left hand end and a singleanchor stitch spaced by three skip stitches or one anchor stitch in eachfour needle operations ormain shaft revolutions following said initialanchor stitches.

Figure 41 is a detail crosssectional View taken on the line 4l-4l onFigure 39.

Figure 42 is a detail cross sectional view taken on the line 42--42 onFigure 39.

Like reference numerals designate corresponding parts throughout theseveral figures of the drawings.

My improved machine embodies a main frame including a base 5, a standard6, an overhanging or laterally extending arm I, and a sewing head 8which is secured to the free end of said arm.

A main shaft 9 equipped with the usual handwh-eel Ill and drive pulley His journaled in the arm and sewing head in bearings I2 and [3, thelatter being in the nature of a long hub mounted wear appearing at thethrust end first.

in the abutting walls of the arm and head and having a U-shapedextension l4 providing an auxiliary bearing portion l spaced from saidhub. See Figures 4, 5 and 33.

Considering the direction of feed of the fabric as being away from theoperator, the head 8 is equipped with a forward extension providing aneedle shaft bearing support portion 16, a complemental stitch formingmechanism support portion I! and a drive housing portion l8.

Rigidly secured as at l9 to the under face of and projecting from thesupport portion I1 is a. horizontal presser foot 20 having formedtherein a longitudinal opening 2| effective during the sewing operationto receive a ridge of material, and a hem guide 22; the latter beingremovably secured as at 23 to said foot.

The stitch forming mechanism includes a reciprocatory needle 24 which isoscillatable angularly across the opening 2| as shown in Figures 5 and27. The needle is attached to a needle arm 25, and the latter is clampedas at 26 to the forward end of an oscillatory needle shaft 21 which isjournaled in a bearing sleeve 28 supported in the bearing supportportion I6. It will be observed by reference to Figures 1, 5 and 32 thatthe sleeve 28 has its end formed in the nature of a split clamp whichfacilitates the taking up of undesirable shaft clearance and thus tendsto assure very accurate needle action. It will be understood thatbearings with a thrust motion at one end wear unevenly, the y taking upslightly at the split clamp end of my improved bearing sleeve 28 wearcan be compensated for and the life of the bearing materially prolonged.The bearing sleeve 28 being only partially split, the desired weartake-up adjustment may be effected without danger of binding the needleshaft 21. The needle shaft 2'! is held against end play by a collar 30.

The crank arm 3| is secured to the needle shaft and is link-connected asat 32 to one end of a forked bell crank lever 33 which is pivoted as at34 in the sewing head 8, the fork embracing a block and eccentricequipment 35 as shown in Figures 5 and 25 so that the rotary motion ofthe main shaft 9 will be transmitted in, the form of oscillatory motionto the needle.

Cooperating with the needle 24 is a complementary stitch formingmechanism for forming a line of lock stitches and which in thisparticular disclosure includes a rotary hook 36 carried by a drivenshaft 31. The shaft 31 is rotated through the means of bevel gear unit38 from a driver shaft 39 rotatably supported in the housing portion l8and which is in turn driven by bevel gear unit 40 with the main shaft 9.It will be observed by reference to Figures 4 and 5 that the hookdriving gear unit 40 is disposed in close relation to the extendedbearing portion l5, and consequently all tendency toward undesirablefiexure or freedom of the main shaft at this point is thus avoided.

A work support or table 4| is pivotally supported at 42 on a horizontalshaft 43 supported in and extending laterally from the frame standard 6in parallelism with the main shaft 9. The support 4| includes anupstanding guard flange portion 44 and a slightly depressed portion 45which extends laterally from said support beneath the presser foot 20 asshown in Figure 1.

A vertically yieldable work clamp 46 is carried by the lateral extension45 and includes a downwardly-turned receiving end 41, openings 48 foraccommodating a feed dog, and an opening 49 for permitting verticallyreciprocatory movement of a ridge forming element.

The work clamp 46 is pivotally supported as at 50 for fore and afttilting movement on a carrier 5| which is in turn pivotally supported at52 for lateral tilting movement on a post 53. The post 53 is verticallyreciprocable in a bore 54 formed in the lateral extension 35 and isyieldably pressed upwardly in opposition to the presser foot 20 byretractile springs 55 anchored in bores 56 and connected to the crosspin 51 secured to the lower end of the post. It will be noted that thepivot 52 of the work clamp is off center and a cushioned spring 58 isprovided to balance the position of said clamp. See Figures 6, 21, 22and 23.

The function of the work clamp 46 is to hold the material securelyduring the sewing operation. When the feed dog has descended, the ridgeforming element rising at this time and coming in contact with thematerial would draw it unevenly if it were not held securely on allsides, causing the needle penetrations to vary. Therefore the work clampis permitted to rock laterally to take care of uneven thicknesses at theright and left hand sides of the ridge forming element, and also to rockfore and aft to take care of the same conditions in front as W811 as inback of the ridge forming element, and

to allow the seam to feed freely. To further accommodate the conditionsstated the work clamp is pivoted off center as shown at 52 in Figure 23.The positioning of the post 53 offcenter also avoids the necessity ofotherwise placing it too far forward, and the coil spring 58 compensatesfor tilting tendencies of the clamp by reason of its off-center mountingand tends to hold the clamp level.

A feed dog 59 is of the usual l-motion type and for effecting thismovement I employ a feed travel shaft 60 and a feed lift shaft 6|, saidshafts being supported beneath the work support 4| in parallelism witheach other and with the main shaft 9. The shaft 66 is provided at itsleft hand end with a crank 62 and the shaft 6| -with a similar crank 63,the former being link-connected as at 64 with the feed dog and thelatter being connected as at 65 to one end of a lever 66 which isconnected at its other end with a lower extremity of the post 53 andintermediately of its ends, by a link 68, with said feed dog. SeeFigures 3, 6, 22 and 23.

At their right hand ends the shafts 60 and 6| are respectively equippedwith cranks 69 and 10, the former being connected by a link H with onearm of a bell crank lever l2 and the latter by a link 13 with one arm ofa bell crank lever '14 both of said bell crank levers being pivotallysupported on the shaft 43. The other arms of the bell crank levers l2and M are connected by pitman and eccentric connections 15 with the mainshaft 9.

It will be readily understood that as the cranks 62 and 63 oscillate theusual l-motion movement will be imparted to the feed dog 59, and that byreason of the connectionof the link 68 intermediately of the ends of thelever 66, each time the feed dog is engaged in the feeding of thefabric, the post 53 will be depressed slightly and the work clamp 46relieved from tight engagement against the fabric and presser foot. Thesprings 55 associated with the work clamp 46 are independent of theplunger. As the feed dog comes up into contact with the material underthe presser foot, the work clamp recedes, allowing the material to befed through freely. When the feed dog has completed its feed travel andmoves down, the springs 55 lift the work clamp against the material tohold it in position with enough pressure to allow the ridge formingelement to stretch the material slightly as it rises to the needlepenetration receiving position.

A ridge forming element or plunger 16 is vertically reciprocable throughthe opening 49 in the work clamp and the opening 2| in the foot forprojecting a ridge or node of hem and body fabric into needlepenetrating position. The ele-' ment i6 is provided with a needleaccommodating notch TI and is adjustably supported on a cam slide orplunger 18 slide guided as at 19 in the work support extension 45 asshown in Figures 20 and 22.

The slide l8 includes a cam receiving cutout portion defined above by anelevation control shoulder 6| and below by a downward movement effectingshoulder 62. Operable in the cutout 36 is a 3-point wiper cam 83 whichis secured at the left hand end of a. shaft 84 rockably supportedbeneath the work support or table 6E. The cam 83 includes a liftingsurface 85 terminating in a nose 86 merging with a con.- centric dwellportion 61 and downward movement effecting surface 88. See Figures 3,1-3, 16 and 20.

At its other end the shaft 84 is equipped with a crank 89 which islink-connected as at 90 to. one end of a lever 9i rockably pivotedintermediate its ends on a shiftable pivot pintle 92. The shiftablepintle is in the nature of a reduced end extending eccentrically from astud shaft 93 rockably supported at 94 beneath the work support ll andhaving av shifter crank or lever 95 secured thereto. The crank 95includes a handle portion 96 projecting above the work support 4ithrough a suitable aperture therein and adapted for association with anindicator scale 91 mounted on said support. A spring pin 98 carried bythe work support 4| cooperates with notches 99 in the crank 95 foryieldably securing said clamp in its positions of adjustment. SeeFigures 6, 12, l4, l5 and 17.

The other end of the lever 9! is connected'by toggle links I06 pivotedtogether as at Hll 'to one arm of a bell crank I02, the other arm of thebell crank being pitman connected as at I63 with an eccentric Hi4mounted on the main shaft 9. See Figures 4, 6 and 12.

A crank disc I65 mounted on a sleeve hub N16 is rotatably supported inthe frame bearing I01 and has a crank pin Hi8 projecting therefrom inspaced relation to the axis of rotation thereof. The crank pin islink-connected as at I69 to the pivotal connection ID! of the togglelinks I00 so that upon rotation of the disc H15 the toggle links will bealternately broken and straightened out. See Figures 9 and 18.

A small gear H0 and a larger gear lllare mounted side by side on themain shaft 9 and respectively mesh constantly with the large and smallergears H2 and H3 secured on the hub sleeves I I4 and I I5 rotatablynested on the sleeve hub I66 as shown in Figure 9. The ratio of thegears is such that for each two revolutions of the main shaft 9 thesleeve hub H5 will be rotated once and for each four revolutions of saidmain shaft the sleeve hub H4 will be rotated once.

The sleeve hub H4 is equipped with a looking or clutching notch H6 andthe hub H5 is equipped with a looking or clutching notch Ill.

In order to provide for eifectively'coupling one or the other of the huband gear combinations I I2, H4, or H3, H5, I provide a shuttle pin IIBwhich is equipped with a cam end II9 projecting from the end of thesleeve hub I06, said pin being opposed at its inner end by a spring I20which constantly tends to project the pin from the sleeve bore in whichit is mounted. A clutch pin I2I projects radially from the shuttle pinand a shifter lever I22 shown in detail in Figure 10 is pivoted at I23to the frame standard between limiting pins I24 and provided with a camsurface I25 for engaging the projecting end of the pin II8 to cooperatewith the spring I20 for shifting the clutch pin I2I into lockingengagement in one or the other of the notches H6 and H1.

It is my purpose in devising the present machine to enable the making of(1) a succession of anchor stitches passing through both the hem and thebody fabric being worked upon, or (2) a plurality of such anchorstitches at the beginning and end of the formation of the hem withalternate skip and anchor stitches intervening the end sets of anchorstitches, or (3) a plurality of such anchor stitches at the beginningand end of the hem operation with intervening anchor stitches formedonly at each fourth needle operation, there being between each pair ofsuch intervening anchor stitches three skip stitches which pass throughthe turnedover or hem fabric only and not through both the hem fabricand the body fabric. These operations are made possible by employment ofthe shiftable pivot pintle 92 and the toggle link and selective gearratio equipments illustrated in Figures 9, 12, 15 and 18. Although Ihave shown and described my invention as being particularly adapted inseaming hems, it will be understood that the machine may be employed inother sewing operations wherein a line of successive anchor stitches maybe formed, or a line of alternate anchor and skip stitches may beformed, or a line of spaced anchor stitches with three skip stitchestherebetween may be formed.

It should be understood that each time the cam nose 86 advances farenough to render any portion of the concentric or dwell cam portion 86effective, the plunger I6 will have been elevated to a point forprojecting a ridge of the hem and body fabric through the opening 2I ofthe foot into needle penetrating position whereby the needle 24 willpenetrate the hem fabric and also the body fabric to form a resultantanchor stitch. When the plunger I6 is elevated to a lesser degree theneedle will penetrate the hem fabric only, to form a resultant skipstitch which does not pass through the body fabric. Whenever the lever95 is shifted to the position shown in Figures 15 and 18 the pivotpintle 92 will have been retracted causing a slight counterclockwisemovement of the shaft 84 as viewed in Figures 15 and 18. The maximum camadvancement movement or lifting of the plunger I6 is accomplished whenthe toggle links I00 are broken to the maximum degree as illustrated inFigures 12, 15 and 18 and when the cooperating eccentric and strapconnectionsIM, I03 are at the maximum throw position illustrated inthese figures, these conditions serving to bring about a maximum ofmovement of the link 90 toward the left as viewed in Figures 12, 15 and18;

In other Words, the maximum lift of the element I6 necessary in theformation of an anchor stitch ordinarily is accomplished'only when themaximum throw of the eccentric and strap connection I04, I03 and themaximum lift of the crank pin I08 and link I09 coincide. Thus when theshuttle pin I I8 is shifted to the position shown in Figure 9 causingthe large gear I I2 and smaller gear IIO to be effective, the maximumeccentric throw and link lift illustrated in Figure 15 will occur onlyonce during each four revolutions of the main shaft 9. During theintervening revolutions of the main shaft 9 the plunger I6 will be onlypartially lifted and will result in the needle penetrating the hemfabric alone and therefore three skip stitches will be formed betweeneach spaced pair of anchor stitches.

When the shuttle pin I I8 is shifted to the right as viewed in Figure 9so as to render effective the gears III, H3, the maximum eccentric throwand link lift will coincide once during each two revolutions of the mainshaft and consequently maximum lift will be imparted to the plunger I6at alternate revolutions of the main shaft and during the interveningalternate revolutions the element will be only partially liftedresulting in the formation of alternate anchor and skip stitches.

Whenever it is desired to form a succession of anchor stitches, it isonly necessary to shift the lever 95 to the position illustrated inFigure 12 of the drawings at which time the pivot pintle 92 will beprojected toward the left causing the link 90 to rotate the shaft 84 aslight bit in the clockwise direction thus slightly advancing the cam83. In this adjustment regardless of the driving ratio of the gearsselected at the moment, the ridge forming element I6 will be lifted themaximum degree at every revolution of the main shaft 9. This is possiblebecause the shifting of the pivot pintle 92 brings about an overthrow ofthe cam 83 as shown in Figure 13 at the intervals, during which themaximum throw of the eccentric and pitman connection I04, I03 and liftof the link I09, coincide, and during each intervening revolution of themain shaft the movement of the cam 83, while less than the maximum, willstill be sufficient to bring the dwell surface 8! into effect causingthe necessary maximum lift of the plunger element I6. Thus it should beclear that with the lever 95 adjusted to the position illustrated inFigure 12, the element I6 will be lifted the maximum degree at eachrevolution of the main shaft 9 regardless of the gear ratio effective atthe time thus causing the needle and complemental stitch formingmechanism to form a succession of anchor stitches which engage both thehem and the body fabric.

As illustrated in Figure 39 a plurality of anchor stitches may be formedat the beginning of the hem and then the lever 95 may be shifted to theposition illustrated in Figure 18 and a series of alternate skip andanchor stitches made, after which the lever may be returned to itsinitial position and the hem operation concluded by a progression ofanchor stitches. It will be observed that in the formation of the hem inFigure 39 the l-to-2 ratio gear unit III, H3 is employed.

In Figure 40 I have shown a fragment of a hem in which three skipstitches are formed intervening each pair of anchor stitches. In theformation of this seam, the lever 95 is shifted to the positionillustrated in Figure 12 and a plurality of anchor stitches formed,after which the lever is shifted to the position shown in Figure 15 andwith the 1-to-4 ratio gear unit IIO, I I2 in use the operation iscontinued forming three skip stitches in advance of each anchor stitch,and at the end of the hem the lever 95 may be shifted back to theoriginal position and without any change of gear ratio the hem may beconcluded by the formation of a succession of anchor stitches.

A lug I26 depends from the work support M and to this lug a latch dogI21 is pivoted as at I28. The dog I21 includes an eccentric lock-sur-'face I 29 and a release lug extension I30. The lock surface I29normally rests on one horizontal leg I3I of a bell crank lever pivotedat I32 on the frame lug I33, the remaining leg I34 of the bell crankextending downwardly and engaging a strong cushioned spring I35 seatedin a frame socket I36. The contact between the leg I34 and the springI35 is made by an adjustable abutment screwI31.

By reason of .the direct contact between the parts I29, I3I, I31, I35downward movement of the work support M is strongly resisted by thespring I35 and the tendency of the spring I35 to force the supportupwardly is suitably resisted by an adjustable stop screw I38 threadedthrough the guard wall 44 and abutting a'stop I39 se-' cured on theframe standard. By provision of this equipment a downwardly yieldablework support is provided and yet the spring I35 is much too strong topermit undesirable downward movement thereof.

When it is desired to lower the support M to insert or remove the work,the operator should not be subjected to the severe labor and strainnecessary to oppose the relatively stronger spring I35 and for thisreason I haveprovided a relatively lighter spring and means whereby thestrong spring may be rendered ineffective and the weaker spring broughtinto play simultaneously with the effort of lowering the support.

It will be observed by reference to Figure 11 that a coil spring I40connected to the support M and the dog I21 serves normally to retain thedog in the position illustrated in Figure 11. The relatively weakerspring above referred tois in the nature of a coil spring I4I coiledabout the stud I42 projecting from the frame lug I33 and. having one endthereof anchored as at I43 to the frame and the other end I44 engagingunder the work support M as shown in Figure 11. A trip lever I45 ispivoted intermediate its ends as at I46 to a lug depending from thesupport 4|. One end of the lever projects under the release lug I30 andto the remaining end a pull chain I41 is secured. By pulling downwardlyon the chain I41 the dog I21 will be tripped to the position illustratedin dotted lines in Figure 11, thus releasing the support 4| from theinfluence of the relatively stronger spring I35 and permitting theoperator-to lower the support by use of the chain I41 resisted only bythe relatively weaker spring I4I. Upon release of the chain the springI40 will return the dog' I31 to the position illustrated in full linesin Figure 11, the eccentric surface I29 facilitating the return tonormal engagement with the bell crank leg I3I.

The strong spring I35 is essential to the attainment of even needlepenetrations because the needle travels in a fixed path and consequentlythe same depth of the ridge of material must be always presented to theneedle. Thus in the formation of anchor stitches it is necessary thatthe ridge forming element rise to the same high position in relation tothe needle, and the work support which carries the element must besubstantially rigid when heavy seams are encountered. The resistance toupward movement of the element must not be solid, however, because ifthe element could not push the material up through the opening in thepresser foot something must yield or break. The spring I35 provides thedesirable strong yet yieldable resistance.

When the operator desires to insert work, a slight pull on the chain I41will release the toggle I45, I21. With the parts in this position thelight spring I4I alone is effective to hold the work support againstdepression and only a slightforce is necessary to be exerted by theoperator to depress the work support 4I sufficiently for inserting thework under the presser foot, or removing work therefrom. In this mannerthe depression of the work support or table 4I may be said to be opposedby a primary means and a secondary means of varying degree, and thatsaid means may be rendered selectively effective.

A safety stop screw I48 may be provided to supplement the function ofthe stop screw I38 and assure against the exerting of excessive pressurecontact between the work clamp and presser foot at any time.

The usual thread tensioning means is indicated at I 49 and includes theusual opposed tensioning plates or discs I50. In order to automaticallyrelease the thread tension whenever the work table or support M isdepressed, I provide a release lever I5I which is pivoted at I52 on themachine frame. The lever includes a crank arm I53 which overlies theguard wall or flange 44 of the support and is equipped with anadjustable abutment screw I54 for engaging said wall. The lever alsoincludes a releasearm I55 which projects into position for engagingbetween the tension plates I50. A coil spring I56 encircles the leverand has its end extended for engagement with the frame release arm I55for holding the abutment screw I54 in engagement with the support wall44. Each time the support is depressed as shown in dotted lines inFigure 24 V of the drawings, the release arm I55 will effect aseparation of the tension plates I 50.

It is desirable to seam a hem with the cross stitch formation as shownin Figures 34 to 36, 39 and 40. In order to make this cross stitch, itis necessary to take the thread from a position above the hem on theright hand side and lay it in the form of a loop in a position under theneedle point on the left hand side of the hem where the needle pointpenetrates the loop as shown in Figures 34 to 36. A novel form of threadlooper is employed for this purpose. To this end a bracket member I51 issecured as at I58 to the presser foot 20 and a pivot block I59 ispivotally supported as at I60 to swing about a vertical axis on saidbracket. The block is cross-grooved to receive a thread looper IBI, saidlooper being pivoted intermediate its ends as at I62 in the groove toswing about a horizontal axis. At one end the looper carries a cam blockI63 provided in its under surface with a guiding cam surface I64 adaptedduring horizontal swinging movements of the looper to ride over a rollerI65 journaled on the bracket member I51 and at its other end the looperrides over a stationary ridge cam I66 secured as at I61 on the presserfoot 20. At its end beyond the ridge cam I66 the looper I6I terminatesin an integral downturned front finger I68 and also carries acooperating .similiarly shaped rear finger I69 yielda

